AA 2500 then UA 3907 at O'Hare
Nashville → Chicago → Washington
Timetable, Chicago time
17:25AA 2500 from Nashville at the gate
12:00UA 3907 to Washington leaves the gate
18 h 35 apart on the timetable, overnight
UA 3907 leaves 18 h 35 after AA 2500 arrives on the timetable: more than half a day, so not a connection we count.